Hepatocyte organoid culture in elliptic hollow fibers to develop a hybrid artificial liver.

A novel organoid culture was developed in which hepatocytes maintain high liver functions for more than several weeks in vitro. The main disadvantage of tissue-engineered organoids is the lack of a blood vessel structure between the aggregated cells. Because of depletion of oxygen, the thickness from the surface of an organoid at which hepatocytes can survive is limited. This study showed that a rat hepatocyte organoid that forms by using centrifugal force in a hollow fiber (HF) had a survival limit thickness of about 80 - 100 microm from the surface of the organoid. Based on the value, we designed an elliptic HF having less than 150 microm minor diameter by using a simple annealing method. All hepatocytes were supplied with oxygen and formed an organoid without a dead cell layer in this HF A hepatocyte organoid in an elliptic HF maintained ammonia removal activity twice as high as in the original HF for at least one month during culture. Albumin secretion activity of an organoid in an elliptic HF was also maintained for at least one month and was the same level as that of liver in a living body. In conclusion, organoid culture by using an elliptic HF seems to be a promising technique to develop a hybrid artificial liver.